Mt.Gox is most likely a target for several factors. 1. The fact that I can deposit in USD and buy bitcoin then transfer those bitcoin anonymously to any where I want in the world, sell those for a currency other than USD and then deposit that currency into a foreign account with no regulation, or taxation is where the US AML (Anti Money Laundering) and KYC (Know Your Customer) policies take effect. Mt.Gox can not reasonably provide an account of transactions to the US Government showing what happened to either the funds or the bitcoin.
IMO this is what they are going to use to begin shutting down all US based funding to any form of bitcoin trading platform.
The US Government has a number of bills in place that they are trying to pass such as SOPA, Online taxation, etc. 25 States in the US already have internet filtering laws. I am sure after the media frenzy a team was assembled to investigate Bitcoin and to see how/if it can in fact be regulated and taxed and when it was determined this would not be possible they have switched gears to shutting it down.
This is exactly how it started when it came to online gambling. Seizure warrants, cease and desists were sent to every financial institution in the states banning them from funding any site that allowed card games and/or games of chance.
For those of you saying Dwolla sucks anyway I agree. However Dwolla is the leading US funding source for MtGox, the most widely used, and widely publicized. If you were trying to send a clear message would you go for the jugular or start with the toes? They don't care about the "little guys" YET.
Tradehill, Coinbase, CampBX, these are all US Based trading platforms. I would keep your eyes on these. If and when any or all of them get shut down for similar issues then you will know without a doubt that the US is moving forward to quietly wipe out Bitcoin.
^^^This. Using Homeland Secuity, also means the U.S. could theoretically have a drone hovering over MtGox by morning. .